1. Field of the Invention
The present invention relates to a suitable image processor and associated image processing program, for example, used in a digital camera or a digital video camera.
2. Description of the Related Art
Conventionally, technology which performs hand shake compensation by image processing is known in the field of digital cameras or digital video cameras. “Hand shake” is also commonly referred to as “camera shake” for camera movement during exposure.
In the conventional prior art, for example, Japanese Laid-Open (Kokai) Patent Application No. 2003-134385 titled “IMAGE SYNTHESIZING DEVICE” discloses a device in which a plurality of images with different light exposures are captured. Within these images, one motion vector as an entire image is detected between one image and the other images. Based on the detected motion vector, the process judges whether or not there is any blurring in the image (motion blur) caused by “object blur” or “hand shake.” In a case of “hand shake,” after alignment of each consecutive image, hand shake compensation is performed and superimposed into one image so that the position displacement of an object, background, etc. corresponding to displacement of the angle of view resulting from “hand shake” can be offset.
Apart from that, in order to accomplish hand shake compensation which superimposes each consecutive image so that the position displacement of an object, background, etc. can be offset, every single image must be captured as a short-time exposure image which does not include hand shake and have a sharpness level which can recognize object and background displacement. Although these requirements are compatible when the photographic environment is sufficiently bright, but either one will be abandoned when the light intensity is insufficient.
Besides, as another method of handshake compensation, there is also technology that makes blurring less noticeable by applying an inverse transform filter to a blurred image. Although, it is possible to apply such technology to each of the above-mentioned brief exposure images, this technique also has a problem.
In the one hand, images with insufficient exposure as mentioned above include a lot of carried noise from the image pickup device. On the other hand, an inverse transform filter for hand shake compensation generally has the characteristic of emphasizing generally high frequency regions. This results in the fact that the noise components in images are emphasized. Consequently, the inverse transform filter does not provide a fundamental solution.